I need help with these easy math questions.?

Question

Plz help me find the G.C.F. and L.C.M. of:

8 and 12,

5 and 7,

9 and 15,

30 and 40,

32 and 48,

52 and 78,

27 and 36,

16 and 13,

4, 6 and 18,

12, 18 and 24,

30, 48, and 120,

11, 44 and 10,

6, 15, 30, and 42.

If you don't want to solve them, please give me a website where I can type in the question and it gives me the answer.
Thank-you so much! (Will pick best answer) =]

Answer 1

Sure, I'll do your homework for you. I did these all in my head. How did I get so good? I practiced, a LOT.... and now you probably won't, so don't complain when you get older and you think algebra is hard because you don't know how to factor, ok?

8 and 12: GCF = 4, LCM = 24.

5 and 7: GCF = 1, LCM = 35.

9 and 15: GCF = 3, LCM = 45

30 and 40: GCF = 10, LCM = 120

32 and 48: GCF = 16, LCM = 96

52 and 78: GCF = 13, LCM = 156

27 and 36: GCF = 9, LCM = 108

16 and 13: GCF = 1, LCM = 208

4, 6 and 18: GCF = 2, LCM = 108

12, 18 and 24: GCF = 6, LCM = 72

30, 48, and 120: GCF = 6, LCM = 240

11, 44 and 10: GCF = 1, LCM = 220

6, 15, 30, and 42: GCF = 3, LCM = 210

=======================================

Just in case you might actually want to get good at this instead of cheating, I'll explain how to do one problem, like the previous answerer.

I'll do the same one as she did, because it's the best one to show you what I want to show you.

30, 48, and 120

For each number, write down its "prime factorization". I'm sure you've been taught how to find it using a "factor tree".

30 = 2 × 3 × 5
48 = 2 × 2 × 2 × 2 × 3
120 = 2 × 2 × 2 × 3 × 5

So if you made a little chart:

         2  3  5
-----------------
30   | 1  1  1
48   | 4  1  0
120 | 3  1  1

That is:

* 30 is made of one 2, one 3, and one 5
* 48 is made of four 2s and one 3
* 120 is made of three 2s, one 3, and one 5.

To find the greatest common factor (GCF) of these numbers, you take the SMALLEST number in each column. The smallest number in the first column is 1, in the second column is 1, and the third column is 0. So the GCF is one 2 times one 3 times zero 5s:

2 × 3 = 6

(Note: if the smallest number in the first column were a 2, the answer would be: 2 × 2 × 3 = 12...the number in the column means how many times you multiply it.)

To find the least common multiple (LCM), you take the LARGEST number in each column. For the 2 column it's 4; for the 3 column, it's 1; for the 5 column, it's 1. So the LCM is four 2s times one 3 times one 5:

2 × 2 × 2 × 2 × 3 × 5 = 16 × 15 = 240

That's the best way to do these problems, rather than writing out all the factors and multiples.

Answer 2

I'll do one for you, then you can figure out how to do the rest:

30, 48 and 120

The factors of
30 are 1, 2, 3, 5, 6, 10, 15, 30
48 are 1, 2, 3, 4, 6, 8, 16, 24, 48
120 are 1, 2, 3, 4, 5, 6, 8, 15, 10, 12, 24, 30, 40, 60, 120

So, the GCF would be the biggest number these three lists have in common.... 6

The multiples of
30 are 30, 60, 90, 120, 150, 180, 210, 240....
48 are 48, 96, 144, 192, 240...
120 are 120, 240, 360...

The LCM is the lowest number these three lists have in common... 240

Answer 3

ok so you are right to divide 27 by 4 and you do get 6.75 a mixed number is a whole number and a fraction this would be 27 over 4 if it were just a fraction but because it is a mixed number you have 6 your whole number and .75 your fraction, but its not in fraction form yet so you look where the decimal point is if you had one number behind the decimal it would be in tenths so .7 would be 7 tenths or 7 over 10 so 7/10 would be your fraction but you have 2 numbers so it will be over 100 so your fraction would be 75/100 but that can be simplified because both numbers can be divided by a comon denominator and the highest common denominator is 25 so when you devide 75 by 25 you get 3 and 100 by 25 gives you 4 so you have 3/4 when you add that to 6 your whole number you get 6 and 3/4 or 6 3/4 which is your final answer

Answer 4

Sorry, people aren't going to do your homework for you. You would have gotten many more answers if you had asked for one problem and asked for someone to show you how to do this type of problem. =)